<template>
  <div class="pagination">
    <button :disabled="pageNo==1 "
      @click=" $emit('getPageNo',startPageAndEndPage.pageNo-1)">上一页</button>
    <button v-show="startPageAndEndPage.start >1" :class="{active:pageNo==1 }"
      @click="$emit('getPageNo',1)">1</button>
    <button v-show="startPageAndEndPage.start>2">……</button>
    <button v-for="(page,index) in startPageAndEndPage.end" :key="index"
      v-show="page>=startPageAndEndPage.start" @click="$emit('getPageNo',page)"
      :class="{active:pageNo==page }">{{page}}</button>
    <button v-show="startPageAndEndPage.end<totalPage-1">……</button>
    <button v-show="startPageAndEndPage.end<totalPage"
      @click="$emit('getPageNo',totalPage)"
      :class="{active:pageNo==totalPage }">{{totalPage}}</button>
    <button :disabled="pageNo==totalPage"
      @click="$emit('getPageNo',pageNo+1)">下一页</button>

    <button style="margin-left: 30px">共 {{total}}条</button>
  </div>
</template>

<script>
export default {
  name: "Pagination",
  props: ['pageNo', 'pageSize', 'total', 'continues'],
  created () {

  },
  mounted () {
  },
  computed: {
    // 计算总共多少页
    totalPage () {
      return Math.ceil(this.total / this.pageSize)
    },
    // 计算出起始页和终止页
    startPageAndEndPage () {
      const { pageNo, totalPage, continues } = this
      let start = 0, end = 0
      if (continues > totalPage) {
        start = 1
        end = totalPage
      } else {
        start = pageNo - parseInt(continues / 2)
        end = pageNo + parseInt(continues / 2)
        if (start < 1) {
          start = 1
          end = continues
        }
        if (end > totalPage) {
          end = totalPage
          start = totalPage - continues + 1
        }
        // console.log(start);
      }
      return { start, end, pageNo }
    }
  }
}
</script>

<style lang="less" scoped>
.pagination {
  text-align: center;
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
}
</style>
